Alternating current distribution system



Oct. 18, 1932. A. H. KEHOE 1,883,236

ALTERNATING CURRENT DISTRIBUTION SYSTEM Original Filed Feb. 1, 1924 WWWW4 :ATTORNEY Patented Oct. 18, 1932 UNITED STATES PATENT OFFICE ARTHUR H.KEHOE, OF RUTHERFORD, NEW JERSEY, ASSIGNOR TO WESTINGHOUSE ELECTRIC &MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA ALTERNATING CURRENTDISTRIBUTION SYSTEM Original application filed February 1, 1924, SerialNo. 690,014. Divided and this application filed August 8,

1929. Serial This application is a division of applicants copendingapplication, Serial No. 690,014 filed Feburary 1, 1924.

This invention relates to systems of alternating-current distributionand particularly to systems of distribution of alternating currents inwhich a plurality of feeder circuits or supply circuits, includingassociated distribution transformers, are adapted to supply energy to acommon secondary low-tension network.

One object of this invention is to provide a system of control wherebythe secondary winding of the distribution transformer may beautomatically connected to a secondary low-tension network when theprimary windingof the transformer is energized through ahigh-tensionprimary circuit from a main supply station and the transformer is inenergy-delivering condition relative to the low-tension network.

Another object of this invention is to provide a distribution system ofthe aboveindicated character that shall have an automatically controlledswitch or interrupter means for disconnecting the secondary winding of atransformer from the low-tension network when the direction of flow ofenergy between the secondary winding of the transformer and thelow-tension network is reversed and that shall automatically reconnectthe transformer to the network when the transformer is inenergy-delivering conditio relative to the network.

This invention, therefore, comprehends an automatic reclosing circuitinterrupter for controlling the connectionand disconnection oftransformers to secondary networks; Iii-this invention, I have providedmeans responsive to the potential difference between the transformer andthe network for controlling the connection of the'transformer to thenetwork and also means responsive to the direction of energy transferbetween the transformer and the network for controlling thedisconnection of the transformer when the energy is fed to thetransformer from the secondary network instead of from the transformerto the secondary network.

Inasmuch as the occurrence of faulty conditions in a high-tension-feedercircuit may cause the disconnection of the feeder circuit from itssource, it is desirable to isolate the transformer from othersource ofenergy supply, such as the secondary network, in order to permit workmento clear with safety the faulty condition in the high-tension circuit.Since the high-tension lines may be disconnected from their source ofenergy at the main station, it is essential that they should not beenergized through the distribution transformers because the transformervoltage, if any, might be sufficient to cause injury to those working ona high-tension line.

In this invention, one of the features relates to the means forpreventing such feedback of energy when the network interrupter is inopen position, and, therefore, the invention has special importance whenthe system involves relatively high voltages.

It is important to provide a system that, in addition to being fullyautomatic in its opening and closing operations, shall avoid theenergization of the high-tension system through the transformer from thenetwork. Therefore, by my invention, I provide a system which meets thecondition of absolute electrical separation of the circuits when thenetwork switch or the network interrupter is open and thus eliminatesentirely any feed back from the network to the high-tension side of thetransformers.

The particular feature of this invention which provides the means forelectrically separating the network from the transformer deals with theuse of interrupter-control means which includes a relay having aplurality of electromagnets, one of the electromagnets being energizedaccording to the voltage on the supply side or transformer side of theinterrupter and tending to close the iiiterrupter and anotherelectromagnet being energized according to the voltage on the load sideor network side of the interrupter and tending to maintain theinterrupter open. The electrical circuits in the relay are entirelyseparate.

This invention will be better understood by reference to the singlefigure of the drawingv which is a diagrammatic view of a systemembodying my invention.

As illustrated, energy may be supplied, through a plurality ofhigh-tension primary circuits 1.and 2, which may be energized from asingle source or independent synchronized sources, to a common net-work8 and distribution transformers 4 and 5. Circuit interrupters 6 and 7are provided for the respective circuits 1 and 2 to be controlled at thestations from which the primary circuits 1 and 2 are energized todisconnect primary windings of the distribution transformers 4 and fromthe energizing source or sources.

In order to control automatically the connection of the secondarywindings of the transformer 4 to the network 3 and disconnectiontherefrom, I provide in each feeder, a network switch or interrupter 8including an operating coil 9 and a voltage relay 10 for controlling thecircuit of the operating coil. Although the circuit interrupter 8 isshown as having a control means, energized in accordance with thenetwork voltage, obviously, control means of other types maybe-utilized, such as a shunt-trip or a current-trip type or alow-voltage trip as disclosed in the copending application of J. S.Parsons, Serial No. 39,947 filed June 27, 1925.

In order to control the operation'of the network switch or interrupter8, I provide a relay 11 of the differential induction type comprisingtwo magnetic elements 12 and 13.

The element 12 is provided with a current winding 14 and a potential orvoltage winding 15 which cooperate to energize the magnetic core 16 insuch manner as to actuate a rotatable disc 17 in the one or the otherdirec tion, according to the degree of energization of the winding 15and the direction of the current in the winding 14.

The current coil 14 is energized from the circuit through a currenttransformer 18 and a saturable transformer 19, the purpose of the latterbeing to limit the value of current which may be caused to traverse thewinding 14. The winding 15 is energized from the transformer side of thenetwork switch 8 in accordance with the voltage of the secondary side ofthe transformer 4.

The element 13 "of-the differential relay 11 is similarly provided witha current winding 21 and a potential winding 22 that cooperate toenergize a magnetizable core 23 to effect the operation of the discmember 17 in theone-or the other direction depending upon the voltageand the direction of energytr versing the windings. course,'that each ofthe elements 12 and 13 is provided with suitable shading coils, orlaglinks 27, as is well understood in the art, and

' in the present invention, I prefer to employ adjustable lag-links, asdisclosed in the abovementioned copending application of J. S.

' Parsons.

It is to be understood, of.

The current winding 21 is energized from the circuit through a currenttransformer 24 and a saturable transformer 25 to preclude the excessiveenergization of the winding 21, The potential winding 22 is energizedfrom the network side of the network interrupter 8 and is energized inaccordance with thevoltage of the network or load circuit 3.

The induction-disc armature 17 is controlled by the respective elements12 and 13 to control the operation of the switch or contact member 26which controls the circuit of the voltage relay 10 associated with theoperating coil 9 of the low-tension switch or interrupter 8.

The several elements of the relay 11 are intended to representwatthour-meter elements and, for the sake of simplicity, are illustratedas C-type magnets. The relay 11 is so calibrated and adjusted that thenetwork voltage alone tends to close the relay contacts or switch 26,while the transformer voltage alone tends to open the relay switch 26.

The relay is so calibrated and adjusted that,

when the transformer voltage is at least equal to that of the network,so that the transformer is in energy-deliverying condition, the torquedeveloped by the transformer voltage through the coil 15 will overcomethe torque developed by the potential winding 22 energized from thenetwork 3, and the switch 26 will, therefore, be opened.

As the switch 26 is opened, the relay 10 closes the circuit of theoperating coil 9 which is thereupon energized from the secondary windingof the transformer 4 to close the network switch 8. The transformer 4 isthereupon connected to the network 3.

As shown, the operating coil 9 closes, the circuit interrupter 8 andmaintains it in closed position so long as the contacts of the relay 10are closed, and, accordingly, so long as the contact 26 of the relay 11is open. \Vhen the contacts of relay 10 are opened, the winding 9 isdeenergized, and the interrupter 8 is permitted to open. It is apparent,however, that various other means for controlling the opening andclosing of the breaker 8 may be employed, as is well understood by thoseskilled in this art.

The relations of the current windings l4 and 21 are such that, whenenergy is delivered to the network 3 in the proper direction, the relay11 will be actuated to maintain the contacts 26 open. However, upon theoccurrence of a condition which effects a reversal. in the direction ofenergy transfer, so that energy is delivered ,to the transformer 4 fromthe network 3, the relay 11 is then operated to close the switch 26,thereupon operating the relay switch 10 to open the circuit of theoperating and holding coil 9. The network interrupter 8 is thereuponpermitted to open, and the transformer 4 is disconnected from the'artare to 40 rupter connected the voltage on the supply I 5.0 the load sideonly of the network 3 until the conditions which caused the reversal inenergy are cleared.

Such a reversal in energy might be caused by a fault in the transformer4 or in the highvoltage circuit supplying the transformer 4, or by thedisconnection of the primary circuit between the transformer and thesource of supply, as, for example, by opening the high-tension switch 6.In the latter case, a reverse energy would be that supplied asmagnetizing energy through the transformer core from the network 3, thelatter of which is energized from other uninterrupted sources, such as,through the transformer 5.

Similar switching equipment and control apparatus is provided for thefeeder circuit associated with the transformer5, but such equipment isnot illustrated or described herein, inasmuch as the construction andoperation of that apparatus is the same as that illustrated inconnection with transformer 4. A special advantage -of this inventionlies in the fact that there is no electrical connection between thenetwork 3 and the transformer 4 when the network switch 8 is inposition. This result is accomplished by means of the specialdifferential relay apparatus 11 already described. For furtherdescription and information, reference may be had to the parentcopending application hereinbefore referred to of which division.

Such changes and modifications in this in- -vention as may be made bythose, skilled in 7 be considered as within the scope of the appendedclaims, excepting that matter which is disclosed by the prior art.

I claim as my invention:

1'. The combination with a circuit-interto a load circuit, ofinterrupter control means including relay apparatus having a pluralityof windings and fluxshifting means associated therewith, one of thewindings being energized according to side only of the interrupter andcooperating with one of the flux-shifting means in such manner to tendto close the interrupter and another winding being energized accordin tothe voltage on the interrupter and cooperating with another of theflux-shifting I -means in such manner to tendto maintain the interrupteropen, said relay apparatus in- I eluding interrupter-opening meansrespon sive to magnitude and phase position of the current through theinterrupter when closed.

2. The combination consisting of a plurality of feeder circuitssupplying a common network load, each feeder circuit including atransformer, a clrcuit interrupter between the transformer and the load,and interrupter control means including relay apparatus having aplurality of windings and flux-shifting means associated therewith, oneof the windings being energized according to the open this is a voltageon the transformer supply side of the interrupter and cooperating withone of the flux-shifting means in such manner to tend to close theinterrupter and another winding being energized according to the voltageon the load side of the interrupter and cooperating with another of theflux-shifting means in such manner to tend to maintain the interrupteropen, said relay apparatus including interrupter-opening meansresponsive to magnitude and phase position of the current through theinterrupter when closeed.

3. The combination consisting of a plurality of feeder circuits forsupplying a common network load, each feeder circuit including ahigh-tension switch, a transformer, a low-tension circuit interrupterbetween the transformer and the load, and interrupter control meansincluding relay apparatus having a plurality of windings andflux-shifting means associated therewith, one'of the windings beingenergized according to the voltage on the transformer side of theinterrupter and cooperating with one of the flux-shifting means in suchmanner to tend to close the interrupter and another windingbeing'energized according to he Voltage on the load side of theinterrupter and cooperating with another of the flux-shifting ineans insuch manner to tend to maintain the interrupter open, said relayapparatus'including interrupter-opening means responsive to magnitudeand Iphase position of the current through the interrupter when closed.

4. The comblnation with a circuit-interrupter connected between atransformer supply circuit and a load circuit, of interrupter controlmeans including closing means having a winding connected to the supplyside only of the interrupter and means cooperating therewith in suchmanner to tend to close the interrupter and having another windingconnected to the load side only of the interrupter and means cooperatingtherewith in such manner to tend to maintain the interrupter open andincluding opening means responsive of the current through theinterrupter.

5. The'combination with a circuit inter-' rupter, of interrupter controlmeans including a differential relay having opposing or bucking elementsfor controlling the closure of the interrupter in accordance with thevoltages on both sides of the interrupter, said control means includinginterrupter-opening means responsive to magnitude and phase a O n Iposition of current flow traverslng the 1nterrupter.

, 6. In an, alternating-current system of distribution, a load circuit,a plurality of feeder' circuits for supplying energy. to said loadcircuit, circuit-interrupting means associated with each feeder circuit,and control means for each of said circuit-interrupting means includinga directional relay, means having to the magnitude and phase position 7.In a system of distribution including two alternating-current circuits,and switching means for connecting said circuits, the combination ofmeans for effecting the automatic opening and reclosing of saidswitching means including a rotatable member and two induction-motorelements for exerting opposed independent torques thereon, said motorelements having current and voltage windings, respectively, the voltagewindings being energized in accordance with the respective voltages ofthe two circuits.

8. In a system of electric distribution including an alternating-currentfeeder circuit, a load circuit, a transformer connected between saidfeeder and load circuits, and 'a circuit interrupter in the secondarycircuit of said transformer, the combination of means for closing saidcircuit interrupter including a movable member, a plurality of motorelements for exerting independent torques on said movable member andhaving windings so connected to said circuits that the resultant torqueon said movable member is a function of the circuit voltages, said meansbeing operative to effect the opening of said circuit interrupterdepending upon the magnitude and phase position of current flowtherethrough.

9. In a system of electric distribution including an alternating-currentfeeder circuit, a load circuit, a transformer connected between saidfeeder and load circuits, and a circuit interrupter is the secondarycircuit of said transformer, the combination of means for controllingsaid circuit interrupter, including relay apparatus having a rotatablemember, a plurality of winding means for exerting independent opposedtorques on said rotatable member and so connected to said circuits thatthe resultant torque exerted on said rotatable membervaries inaccordance -with the difference between the voltage magnitudes of therespective circuits when the circuit interrupter is open andinaccordance with the magnitude and phase position of current flow whenthe circuit interrupter is closed. i

10. In a system of electric distribution including a plurality ofalternating-current feeder circuits, a load circuit, a transformerconnected between each feeder circuit and said load circuit, and acircuit interrupter in the secondary circuit of each transformer, thecombination of control means for each circuit interrupter including arotatable member and two induction-motor elements for exertinindependent opposed torques thereon an having energizing windings soconnected to said circuits as to effect a resultant torque in adirection to close said circuit interrupter under predetermined feederand load-circuit voltage conditions and to open said circuitinterrupterdepending upon the magnitude and phase position of current flow there-Jciated therewith, means for energizing one of said motor elements toeffect a torque on said rotatable member in accordance with themagnitude of the feeder-circuit voltage and means for energizing theother sai motor element to effect an opposed torque on said rotatablemember in accordance with the magnitude of the load-circuit Volta e whensaid circuit interrupter is open, sai cont-r01 means being operative toeffect the opening of said circuit interrupter when the current flow isfrom the load circuit to the feeder circuit.

circuits, a load circuit energized thereby, and switching means forconnecting each of said feeder circuits and said load circuit, thecombination of control means for each of said switching means includingrelay apparatus having a rotatable member and two induce tion-motorelements associated therewith for exerting opposing torques, and meansfor energizing said motor elements from said circuits in such manner asto preclude the actuation of said control means to close the circuitinterrupter under predetermined system conditions, said relay apparatusbeing o erative to open the circuit interrupter depen in upon themagnitude and phase position 0 current flow therethrough.

13. .In an alternating-current network system of distribution,aplurality of feeder cir- 12. In an alternating-current network system ofdistribution, a plurality of feeder cuits, a load circuit, and switchingmeans connecting each of said feeder and load circuits, the combinationof means for controlling the automatic opening and reclosing of each ofsaid switching means including directional relay means having a movablemember and two independent torque-producing means energized from saidcircuits for cooperating with said movable member, there being noelectrical connection between said load and feeder circuits through saidcontrol means when said switching means is open.

14. In a means for controlling the automatic opening and reclosing of aswitching means connected between an alternating-current feeder circuitand a load circuit, the combination of relay apparatus having a rotata-'ble member and two induction-motor elements energized from saidcircuits for effecting independent opposed torques on said movablemember, said control means being efiectively energized to close saidswitching means depending upon the magnitudes of the respective feederand load-circuit voltages and to open said switching means dependingupon the magnitude and phase position of current flow therethrough.

1 5. In a control means for the automatic opening and reclosing of aswitching means connected between an alternating-current feeder circuitand a load circuit, the combination of directional relay apparatusincluding a rotatable member, two independent torqueproducing meansassociated therewith, said torque-producing means being energized 1naccordance with the current and Voltage of said circuits, there being noelectrical connection between said circuits through said control meanswhen said switching means is open.

In testimony whereof, I have hereunto sub-.

scribed my name this 22nd day of July, 1929.

ARTHUR H. KEHOE.

